Question

What is the mass number of nitrogen if the protons, electrons, and neutrons are all equal?
Responses

12
12

13
13

14
14

18
18

Answer 1

The mass number of an atom is the sum of the number of protons and neutrons. If the number of protons, electrons, and neutrons are all equal, we can denote the number of protons as \( p \), electrons as \( e \), and neutrons as \( n \). In this case, we have:

- Protons (\( p \)) = Electrons (\( e \)) = Neutrons (\( n \)) = \( x \)

The mass number \( A \) is calculated as:

\[
A = p + n = x + x = 2x
\]

For nitrogen, the atomic number (number of protons) is 7, which means it has 7 protons and, in a neutral atom, also 7 electrons. If we were to have equal numbers of protons, electrons, and neutrons, we'd have \( p = e = n = x = 7 \). Therefore:

\[
A = 7 + 7 = 14
\]

Thus, the mass number of nitrogen, when protons, electrons, and neutrons are all equal, is 14.

The correct response is:

14